Electric-railway system.



No. 050,304. Patented may 29, |900. A. H. ARMsTnoNG. ELECTRIC RAILWAY SYSTEM.

(Application filed Apr. 8, 1899.)

(N0 Model.)

L@ -L E E c a u E j E E *luf .un H u L M L MLK m n@ L d@ l Invent OY:

UNITED STATES PATENT OFFICE.

ALBERT II. ARMSTRONG, OF SCIIENECTADY, NEV YORK, ASSIGNOR 'lO THE GENERAL ELECTRIC COMPANY, OF NEW YORK.

ELECTRIC-RAILVVAY SYSTEM.

SPECIFICATION forming par't of Letters Patent No. 650,364, dated May 29, 1900.

Application filed April 8, 1899. Serial No. 712,212. (No model.)

Zo all whom it may concern.-

Be it known that I, ALBERT H. ARMSTRONG, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Electric-Railway Systems, (Case No. 1,0G2,) of which the following is a specification.

In supplying current to third-rail or other electric-railway systems equipped with alternating-current motors it has been proposed to use a central generating-station producing multiphase current of high tension and to transmit this current to various step-down transformers along the line of the road and to connect the secondaries of each transformer or set of transformers to supply-conductors comprising the track-rails and one or more third rails or trolley-wires. in general preferable, as railways which it is proposed to operate by alternating current are usually long-distance high-speed roads owning their own right of Way. In any case this arrangement involves either an enormous number of transformers or the transmission of current to the motors through a considerable length of supply-conductor. Vith the preferred construction-two iron third rails in two sides of a three-phase or two-phase system and the two track-rails in multiple in the other side-each car will receive current on the average through a heavy iron conductor duction in the line.

in each leg of the circuit of a length equal to about one-quarter of the distance between transformers, while in some positions the path through iron will be equal to half the distance between transformers for each leg of the circuit.

Now alternating current railways commonly employ induction-motors, which themselves have more or less self-induction and which are particularly sensitive to self-in- The passage of the lowtension alternating currents, necessarily of some considerable volume, through any considerable length of iron conductor produces an inductive drop such as to sometimes practically wipe out the impressed voltage as the carstarts and in all cases to seriously interfere with the operation of the motors. The sup- Third rails are rangement is very expensive and introduces large losses, due to the magnetizingcurrent, dac., of the transformer, so that in practice it cannot be carried very far. Even if third rails of copper or other non-magnetic material or trolley-wires sufticientl y heavy to carry the large currents needed should be employed there would still be an inductive drop in the track-rails, which would With this arrangement seriously unbalance the system. Obviously each transformer in the system above set forth may be replaced by a generating-station, an inverted rotary,77 or any other source of alternating current; but the difficulties above set forth will still persist, usually in an even greater degree. I am able to avoid these troubles by employing only a reasonable number of sources of current and connecting each of them to the track-rails and to the third rails or, speaking more generally, to the inductive conductors at a number` of different points by heavy leads of copper or other non-magnetic conducting metal, constituting a substantially-non-inductive system. These conductors are preferably arranged in a triple non- A inductive cable. In my improved system in its best form I use one or more multiphase generating-stations, leads or feeders extending therefrom, a reasonable number of stepdown transformers in multiple from the leads, and iron or steel conductors (which are best adapted to withstand heavy strains and rough usage) connected to the secondaries of the transformer by non-inductive cables, each secondary feeding the line at a number of different points. In this way I may use only a limited number of transformers, sufcient for the most economical distribution, rst cost and losses being considered, and yet reduce the maximum inductive path through Whichcurrent must pass to a minimum.

In the drawings attached to this specification, Figure 1 is a diagram of a railway sys- IOO tem or a portion thereof embodying my in: ventlon, and Flg. 2 is' a cross-section of al viously single-phase currents, two-phase curf rents,lor any other desired alternating currents may be employed.

and D D2 are the third rails or conductors, extending along the line of the road. der to supply current to the third rails Dl D2 and to the track-rails C C, I carry the conductors B B2 B3 substantially the whole length of the railway and connect these conductors by feeders or otherwise to points at which I wish to locate the transformers T' T2 T3, (he. Each of these transformers is here shown as of the open-delta type; but obviously three transformers connected in Y orin delta or with their primaries in Y and their secondaries in delta or arranged in any other way to transform.

the particular currents employed maybe used in place -of each of the transformers T T2 TS. The primaries of these transformers are 'supplied, as shown, from the generator A through the lines B B2 BS. The secondaries are each connected at a plurality of points to the third rails D and D2 and to the track-rails C. As

` T2 T3 and is also connected to the track-rails C C and to the third rails D' D2 at a number of points of conductors F F F. Inthis way I am enabled to supply current to the car I have shown in this application In orirrespective of Where it may be located on the road i-n such a way that no considerable reactive electromotive force shall be created outside of the motor itself.

What I claim as new, and desire to secure by Letters Patent of the United States, is-l 1. In combination, in an alternating-curiI rent electric-railway system, supply-conductors, constituting an inductive conducting' system, a pluralityof sources of alternatingcurrent supply arranged at intervals along the railway, and a substantially=noninduct G C are the tracklrails of a railway system,

ive system of conductors connecting each of said sources to a plurality of points on the 2. In combination, in an alternatingcu'rrent electric-railwaysystem, supply-conduc-4 tors constitutingan inductive conducting system, and comprising track-rails `of magnetic material, a substantiallynominductive sys-Y tem of conductors extending along the railway, a plurality of sources of alternating-current supply 'arranged at intervals along the road and connected tosaid non-inductive system and more numerous connections between said non-inductive'sys'tem and said supplyconductors.

3. In combinatiom'a generator of alternat ing currents, 'a plurality of transformers supplied in multiple arc therefrom, an electric railway adapted to be operated by alternating currents, iron or steel supply-conductors for said railway, a non-inductive or 4substantially-non-inductive system of conductors extending along the line of the road, electrical connections from the secondary of each ofthe transformers of said non-inductive system, and more n n-'morons connections between said system and said supply-conductors.

In witness whereof I have hereunto set my hand this 6th day of April, 1899.

ALBERT H. ARMSTRONG.

Vitnesses:

BENJAMIN B. HULL, MABEL E. JAcoBsoN. 

